Question Issues with clipping in DrawMeshInstanced and shader

I'm very bad with shaders, and I'm using one I copied from an article I read online about DrawMeshInstanced. I'm making a 2D game and some of the meshes are clipping into some of the others. Here's an example of the bug: https://i.imgur.com/Bj1U7e0.gif

Here's the shader I'm using:

Shader "Custom/DMIColor2"

{

Properties

{

_MainTex("Texture", 2D) = "white" {}

_Color("Color", Color) = (1,1,1,1)

}

SubShader

{

Tags { "Queue" = "Transparent" "IgnoreProjector" = "True" "RenderType" = "Transparent" }

LOD 100

Cull Back

ZWrite On

Blend SrcAlpha OneMinusSrcAlpha

Pass

{

//ZWrite Off

CGPROGRAM

#pragma vertex vert

#pragma fragment frag

#pragma multi_compile_instancing

#include "UnityCG.cginc"

struct appdata

{

float4 vertex : POSITION;

UNITY_VERTEX_INPUT_INSTANCE_ID

float2 uv : TEXCOORD0;

};

struct v2f

{

float2 uv : TEXCOORD0;

float4 vertex : SV_POSITION;

UNITY_VERTEX_INPUT_INSTANCE_ID

};

sampler2D _MainTex;

//float4 _MainTex_UV;

UNITY_INSTANCING_BUFFER_START(Props)

UNITY_DEFINE_INSTANCED_PROP(fixed4, _Color)

UNITY_DEFINE_INSTANCED_PROP(fixed4, _MainTex_UV)

UNITY_INSTANCING_BUFFER_END(Props)

v2f vert(appdata v)

{

v2f o;

UNITY_SETUP_INSTANCE_ID(v);

UNITY_TRANSFER_INSTANCE_ID(v, o);

float3 worldPosition = float3(v.vertex.x, v.vertex.y, -v.vertex.y / 100);

o.vertex = UnityObjectToClipPos(float4(worldPosition, 1.0f));

o.uv = (v.uv * UNITY_ACCESS_INSTANCED_PROP(Props, _MainTex_UV).xy) + UNITY_ACCESS_INSTANCED_PROP(Props, _MainTex_UV).zw;

return o;

}

fixed4 frag(v2f i) : SV_Target

{

UNITY_SETUP_INSTANCE_ID(i);

fixed4 col = tex2D(_MainTex, i.uv) * UNITY_ACCESS_INSTANCED_PROP(Props, _Color);

clip(col.a - 30.0 / 255.0);

col.rgba *= col.a;

return col;

}

ENDCG

}

}

}

The shader is supposed to handle depth sorting using the Z coordinate, so that things with lower Y on the screen render on top of things with higher Y on the screen.
I'm setting the Z like this in my C# code when I populate the arrays for using with DrawMeshInstanced: "position.z = -10 + position.y * 0.01f;"

The draw portion of my code is:

block.SetVectorArray(uvShaderId, local_uvs);

block.SetVectorArray(colorShaderId, local_colors);

Graphics.DrawMeshInstanced(mesh, 0, material, local_matrices, b, block);

local_uvs, local_matrices, and local_colors are arrays with the obvious data. b is just the slice size, and block is the MaterialPropertyBlock. It all works fine for thousands of meshes, except I have this little clipping issue.
My previous solution was one I wrote myself, using a mesh with verts and uvs generated every frame. It worked, with no objects clipping through others, but it was a little bit slower.

I would appreciate any help. Thanks.